76 THE PROSPECTOR'S HANDBOOK. 



Lustre metallic. 



Colour and Streak black or iron grey. 

 H. 2 to 2-5; S.G. 6-29. 



Composition When pure contains about 71 per cent, of 

 silver, the rest antimony, &c. 



With carbonate of soda before B.F. it decrepitates, but 

 readily yields a silver lead. If the mineral be dissolved in 

 nitric acid a piece of bright copper will be covered by a film 

 of silver if placed in the solution. It is distinguished from 

 silver glance by being brittle ; whereas silver glance is soft 

 and sectile, and chips can be cut off without crumbling. 



Silver Glance (sulphide of silver). 

 A most important ore. Found massive, &c. 



Crystallization cubical, octahedral, &c. 



Fracture conchoidal or uneven. 



Colour blackish or lead grey (before exposure to the 



light has a bright metallic lustre). 

 Streak same as colour, and shining. 

 Structure soft and sectile. 

 H. 2 to 2-5; S.G. 7'1 to 7-4. 



Contains 87 per cent, silver, the rest sulphur. Is usually 

 associated with the sulphides of lead, copper, iron, zinc, 

 antimony, arsenic, &c., also with nickel and cobalt ores. 



Before B.F. with carbonate of soda yields globule of 

 metal. Known in acid solution by usual tests. Is similar 

 in appearance to some copper and lead ores, but distinguished 

 before the B.F. and by its malleability. Is fusible at the 

 temperature of an ordinary flame. 



Horn Silver (chloride of silver). 



A soft mineral found massive ; also in crystals. Is nearly 

 opaque, translucent on the edges, and has a waxy appear- 

 ance. 



Fracture conchoidal. 



Colour greenish white, pearl grey, brownish, dirty 



green, &c., and on exposure, brownish or purplish, 



&c. 

 Streak Shining and grey. 



